Wireless resource scheduling method and device for NAN

ABSTRACT

A wireless resource scheduling method and device for NAN are disclosed. The wireless resource scheduling method for NAN can comprise the steps of: determining switching from a WiFi mode to a NAN mode by a NAN terminal of an AP function; when the NAN terminal of the AP function determines the switching to the NAN mode, transmitting a CTS-to-self frame on the WiFi mode by the NAN terminal of the AP function; switching from the WiFi mode to the NAN mode by the NAN terminal of the AP function; and transmitting, by the NAN terminal of the AP function, a NAN frame to a NAN terminal on the NAN mode, wherein the WiFi mode supports communication on the basis of a BSS and the NAN mode can support communication on the basis of a NAN cluster.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage filing under 35U.S.C. 371 ofInternational Application No. PCT/KR2015/009252, filed on Sep. 2, 2015,which claims the benefit of U.S. Provisional Application No. 62/046,147,filed on Sep. 4, 2014, the contents of which are all hereby incorporatedby reference herein in their entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to wireless communication, and moreparticularly, to a radio resource scheduling method and apparatus forneighbor awareness networking (NAN).

Related Art

There is a growing demand for a proximity-based service for transmittingand receiving data between users in close proximity and applicationtechnologies based on the proximity-based service. Recently, with theexplosive use of mobile Internet devices such as a smart phone, atablet, or the like, there is a need for a device-to-device (D2D)communication technology which provides a new proximity-based servicecapable of guaranteeing a wider transmission range and a higher qualityof service (QoS) than the conventional D2D communication technology suchas Bluetooth or wireless fidelity (WiFi) peer to peer (P2P). The D2Dcommunication technology may be utilized in various services such ascommercial services, public safety related services, or the like.

WiFi Alliance (WFA) has been conducting research to support low powerdiscovery between a plurality of terminals (or stations (STAs)) since2011, and completed the draft specification 1.0 in May 2013. Unlike IEEE802.11aq, the WFA supports mutual discovery between terminals without anaccess point (AP) in an independent basic service set (IBSS) environmentof IEEE 802.11, and uses a synchronous-type protocol. Interworking witha WiFi P2P specification is taken into consideration in directcommunication performed between terminals after the discovery betweenthe terminals.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a radio resourcescheduling method for neighbor awareness networking (NAN).

It is another object of the present invention to provide a radioresource scheduling apparatus for NAN.

According to an aspect of the present invention, a method of schedulinga radio resource for neighbor awareness networking (NAN) may include:determining switching from a wireless fidelity (WiFi) mode to a NAN modeby a NAN terminal in access point (AP) capability; if the NAN terminalin AP capability determines the switching to the NAN mode, transmitting,by the NAN terminal in AP capability, a clear to send (CTS)-to-selfframe on the WiFi mode; switching, by the NAN terminal in AP capability,from the WiFi mode to the NAN mode; and transmitting, by the NANterminal in AP capability, a NAN frame to the NAN terminal on the NANmode. The WiFi mode may support communication based on a basic serviceset (BSS). The NAN mode may support communication based on a NANcluster.

According to another aspect of the present invention, a NAN terminal inAP capability for performing radio resource scheduling for NAN mayinclude: a radio frequency (RF) unit configured for transmitting orreceiving a radio signal; and a processor operatively coupled to the RFunit. The processor may be configured for: determining switching from aWiFi mode to a NAN mode; if the switching to the NAN mode is determined,transmitting a CTS-to-self frame on the WiFi mode; switching from theWiFi mode to the NAN mode; and transmitting a NAN frame to the NANterminal on the NAN mode. The WiFi mode may support communication basedon a BSS. The NAN mode may support communication based on a NAN cluster.

Radio resources can be effectively allocated without waste of power to aneighbor awareness networking (NAN) terminal operating based on a NANmode and a WiFi mode station (STA) operating based on a WiFi mode on thebasis of radio resource scheduling performed by a NAN terminal in accesspoint (AP) capability for switching between the WiFi mode and the NANmode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual view illustrating a structure of a wireless localarea network (WLAN).

FIG. 2 is a conceptual view illustrating a clear to send (CTS)-to-selfmechanism.

FIG. 3 and FIG. 4 are conceptual view illustrating a neighbor awarenessnetworking (NAN) cluster.

FIG. 5 is a conceptual view illustrating a structure of a NAN terminal.

FIG. 6 and FIG. 7 are conceptual views illustrating a relationshipbetween NAN components.

FIG. 8 is a conceptual view illustrating a role and state of a NANterminal.

FIG. 9 is a conceptual view illustrating a NAN mode operation of a NANterminal in access point (AP) capability.

FIG. 10 is a conceptual view illustrating an operation of a NAN terminalin AP capability in a NAN mode according to an embodiment of the presentinvention.

FIG. 11 is a conceptual view illustrating a CTS-to-self frame accordingto an embodiment of the present invention.

FIG. 12 is a conceptual view illustrating a CTS-to-self frame accordingto an embodiment of the present invention.

FIG. 13 is a block diagram illustrating a wireless device according toan embodiment of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 is a conceptual view illustrating the structure of a wirelesslocal area network (WLAN).

An upper part of FIG. 1 illustrates the structure of an infrastructurebasic service set (BSS) of institute of electrical and electronicengineers (IEEE) 802.11.

Referring the upper part of FIG. 1, the wireless LAN system may includeone or more infrastructure BSSs 100 and 105 (hereinafter, referred to asBSS). The BSSs 100 and 105 as a set of an AP and an STA such as anaccess point (AP) 125 and a station (STA1) 100-1 which are successfullysynchronized to communicate with each other are not concepts indicatinga specific region. The BSS 105 may include one or more STAs 105-1 and105-2 which may be joined to one AP 130.

The BSS may include at least one STA, APs providing a distributionservice, and a distribution system (DS) 110 connecting multiple APs.

The distribution system 110 may implement an extended service set (ESS)140 extended by connecting the multiple BSSs 100 and 105. The ESS 140may be used as a term indicating one network configured by connectingone or more APs 125 or 230 through the distribution system 110. The APincluded in one ESS 140 may have the same service set identification(SSID).

A portal 120 may serve as a bridge which connects the wireless LANnetwork (IEEE 802.11) and another network (e.g., 802.X).

In the BSS illustrated in the upper part of FIG. 1, a network betweenthe APs 125 and 130 and a network between the APs 125 and 130 and theSTAs 100-1, 105-1, and 105-2 may be implemented. However, the network isconfigured even between the STAs without the APs 125 and 130 to performcommunication. A network in which the communication is performed byconfiguring the network even between the STAs without the APs 125 and130 is defined as an Ad-Hoc network or an independent basic service set(IBSS).

A lower part of FIG. 1 illustrates a conceptual view illustrating theIBSS.

Referring to the lower part of FIG. 1, the IBSS is a BSS that operatesin an Ad-Hoc mode. Since the IBSS does not include the access point(AP), a centralized management entity that performs a managementfunction at the center does not exist. That is, in the IBS S, STAs150-1, 150-2, 150-3, 155-4, and 155-5 are managed by a distributedmanner. In the IBSS, all STAs 150-1, 150-2, 150-3, 155-4, and 155-5 maybe constituted by movable STAs and are not permitted to access the DS toconstitute a self-contained network.

The STA as a predetermined functional medium that includes a mediumaccess control (MAC) that follows a regulation of an Institute ofElectrical and Electronics Engineers (IEEE) 802.11 standard and aphysical layer interface for a radio medium may be used as a meaningincluding all of the APs and the non-AP stations (STAs).

The STA may be called various a name such as a mobile terminal, awireless device, a wireless transmit/receive unit (WTRU), user equipment(UE), a mobile station (MS), a mobile subscriber unit, or just a user.

FIG. 2 is a conceptual view illustrating a CTS-to-self mechanism.

In FIG. 2, it is disclosed a case of sensing a medium by using a methodof exchanging a request to send (RTS) frame and a clear to send (CTS)frame and a case of sensing a medium using a CTS-to-self frame.

The IEEE 802.11g standard defines a CTS-to-self protection mechanism.The CTS-to-self protection mechanism may be used in place of a mediumsensing mechanism using RTS and CTS frames. In case of the CTS-to-selfprotection mechanism, a medium overhead can be decreased in comparisonwith the media sensing mechanism using the RTS/CTS frames.

Referring to the left side of FIG. 2, a method of exchanging an RTSframe and a CTS frame before transmitting a data frame at a transmittingend may be performed as follows.

A case where an STA A 200 intends to transmit a data frame to an STA C210 is assumed in the left side of FIG. 2.

1) The STA A 200 first transmits an RTS frame 220.

2) The transmitted RTS frame 220 is transmitted to an STAB 205 and theSTA C 210 which are present in a carrier sensing range.

3) The STA B 205 and the STA C 210 transmit CTS frames 225 and 230.

4) The transmitted CTS frames 225 and 230 are transmitted to the STA A200, the STAB 205, the STA C 210, and an STA D 215.

The STA D 215 is located out of the carrier sensing range of the STA A200, and thus cannot not receive the RTS frame 220 from the STA A 200(That is, the STA D 215 is a hidden node of the STA A 200). However, byreceiving the CTS frame 230 from the STA C 210, it can be known that theSTA A 200 occupies a medium to transmit data.

5) The STA A 200 transmits a data frame to the STA C 210.

Referring to the right side of FIG. 2, a medium sensing mechanism usinga CTS-to-self frame and performed before transmitting a data frame at atransmitting end may be performed as follows. A case where an STA A 250intends to transmit a data frame to an STA C 260 is assumed in the rightside of FIG. 2.

1) The STA A 250 transmits a CTS-to-self frame to an STA B 255 and theSTA C 260 which are present in a carrier sensing range.

2) The STA B 255 and STA C 260 which have received the CTS-to-self framedefer transmission of another data frame to receive the data frametransmitted from the STA A 250.

A neighbor awareness technology is under research in WiFi alliance(WFA). The neighbor awareness technology can discover a service forvarious applications by transmitting a small amount of messages whileoperating in a background mode in the STA.

When using the neighbor awareness technology, the STA may discover aneighbor service before connecting to a service providing device. Afterthe service is discovered by using neighbor awareness networking (NAN),the STA may execute an application and connect to Wi-Fi Direct or theexisting WLAN network to use a corresponding service.

The NAN needs to be designed to operate smoothly in crowded environmentsand indoors and to minimize power consumption. After the STA exchangesinformation on available services with other STAs through the NAN, theSTA may opt-in a connection with a discovered STA. The STA and thediscovered STA may be connected through a direct connection betweendevices.

Hereinafter, the STA or AP communicating based on the NAN may beexpressed as a NAN terminal. In particular, among the NAN terminals, aNAN terminal which creates a NAN cluster may be expressed by the term“anchor master”. At least one NAN terminal among NAN terminals includedin the NAN cluster may be the NAN master.

Hereinafter, a neighbor awareness networking (NAN) topology isdisclosed. A NAN network may consist of NAN terminals which use a set ofthe same NAN parameters (e.g., a time duration between consecutivediscovery windows, a duration of a discovery window, a beacon interval,a NAN channel, or the like.). The NAN terminals may constitute a NANcluster. The NAN cluster may be a set of NAN terminals which use a setof the same NAN parameters and operate in synchronization with the samediscovery window schedule.

FIG. 3 and FIG. 4 are conceptual view illustrating a NAN cluster.

Referring to FIG. 3, a NAN terminal belonging to the NAN cluster maydirectly transmit a NAN service discovery frame in a multicast/unicastmanner to another NAN terminal within a range of a discovery window.

Referring to FIG. 4, as described above, one or more NAN masters may bepresent in the NAN cluster, and the NAN master in the NAN cluster may bechanged. In addition, the NAN master may transmit all of a NANsynchronization (or sync) beacon frame, a NAN discovery beacon frame,and a NAN service discovery frame.

The NAN sync beacon frame may be used for synchronization of NANterminals in the NAN cluster. The NAN discovery beacon frame may be usedfor the purpose of advertising to NAN terminals which are not registeredto the NAN cluster so that the cluster can be discovered. The NANservice discovery frame may be used for the purpose of exchanginginformation on a service between respective NAN terminals by advertisingthe service between the NAN terminals included in the NAN cluster.

FIG. 5 is a conceptual view illustrating a structure of a NAN terminal.

Referring to FIG. 5, the NAN terminal is based on the 802.11 physicallayer, and has a NAN discovery engine, a NAN medium access control(MAC), and NAN application programming interfaces (APIs) towardsrespective applications (application 1, application 2, . . . ,application N) as primary components.

FIG. 6 and FIG. 7 are conceptual views illustrating a relationshipbetween NAN components.

Referring to FIG. 6 and FIG. 7, a service request and response ispressed through a NAN discovery engine, and a NAN MAC processes NANbeacon frames and NAN service discovery frames. The NAN discovery enginemay provide subscribe, publish, and follow-up functions.

The publish/subscribe function is performed through a service interfacefrom a service/application. When a publish/subscribe command isexecuted, an instance of the publish/subscribe function is created. Eachinstance is driven independently, and several instances may be drivenconcurrently according to an implementation. The follow-up function is ameans for a service/application for transmitting/receivingservice-specific information.

FIG. 8 is a conceptual view illustrating a role and state of a NANterminal.

Referring to FIG. 8, the NAN terminal may operate as a NAN master forperforming a master role. In addition, the role of the NAN master of theNAN terminal may be changed to another role. That is, the NAN terminalmay transition to several roles and states.

The roles and states allowed for the NAN terminal may be a master(hereinafter, the master is a master role and sync state), a non-mastersync, a non-master non-sync, or the like. According to the role andstate of the NAN terminal, whether it is possible to transmit a NANdiscovery beacon frame and/or a NAN sync beacon frame may be determined.

Table 1 below shows whether it is possible to transmit the NAN discoverybeacon frame and/or the NAN sync beacon frame according to the role andstate of the NAN terminal.

TABLE 1 Role and NAN synchronization state NAN discovery beacon framebeacon frame Master transmission is possible transmission is possibleNon-Master transmission is impossible transmission is possible SyncNon-Master transmission is impossible transmission is impossibleNon-Sync

The state of the NAN terminal may be determined through a master rank.The master rank represents an intention of a NAN terminal which intendsto operate as a NAN master. That is, a master rank having a great valuerepresents a high preference for the NAN master of the NAN terminal.According to a master preference, a random factor, and a device MACaddress, a NAN MR may be determined by Equation 1 described below.MasterRank=MasterPreference×2⁵⁶+Randomfactor×2⁵⁶+MAC[5]×2⁴⁰+. . .+MAC[0]  <Equation 1>

The master preference, the random factor, and the device MAC address maybe indicated based on a master indication attribute included in the NANbeacon frame. The master indication attribute may be as shown in Table 2below.

TABLE 2 Field Name Size Value Description Attribute ID 1 0x00 Identifiesthe type of NAN attribute Length 2 2 Length of the following field inthe attribute Master Preference 1 0-255 Information that is used toindicate a NAN Device preference to serve as the role of Master, with alarger value indicating a higher preference Random Factor 1 0-255 Arandom number selected by the sending NAN Device

In regards to the master rank, the NAN terminal which activates the NANservice and starts the NAN cluster sets both of the master preferenceand the random factor to 0, and resets NANWarmUp. The NAN terminal shallset a value of the master preference in the master indication attributeto a value greater than 0 and set a value of the random factor in themaster indication attribute to a new value until the NANWarmUp expires.

The NAN terminal joined to the NAN cluster having the master preferenceof the NAN master set to a value greater than 0 may set the masterpreference to a value greater than 0 regardless of whether the NANWarmUpexpires, and may set the random factor to a new value.

The NAN terminal may operate as the NAN master of the NAN clusteraccording to the value of the master rank. That is, all NAN terminalsincluded in the NAN cluster have capability to operate as the NANmaster. The NAN master has the greatest master rank in the NAN cluster.Further, the NAN master has a value of 0 as an HC (Hop count to theAnchor Master) value. The NAN master may have the smallest AMBTT (AnchorMaster Beacon Transmit Time) value among the NAN terminals included inthe NAN cluster.

A plurality of NAN masters may be present temporarily in the NANcluster. However, in principle, one NAN master may be present in the NANcluster. A NAN terminal which becomes a NAN master in the pre-existingNAN cluster may directly use a time synchronization function (TSF) usedin the pre-existing NAN cluster.

In the following case, the NAN terminal may start a new NAN cluster, orthe NAN terminal may become a NAN master according to a change in themaster rank. Alternatively, if a beacon frame is no longer received fromanother NAN terminal currently operating as the NAN master, the NANterminal may become the NAN master. In addition, if a received signalstrength indication (RSSI) of other NAN terminals among the NANterminals belonging to the NAN cluster is decreased to be less than orequal to a specific level, the NAN terminal may autonomously become theNAN master. NAN terminals participating in the same NAN cluster may besynchronized to a common clock. The TSF of the NAN cluster may beimplemented by a distributed algorithm which must be performed in allNAN terminals. Each NAN terminal participating in the NAN cluster maytransmit NAN sync beacon frames according to the distributed algorithm.

The NAN terminal may synchronize a clock during a discovery window. Thediscovery window has a length of 16 Time Units (TUs). During thediscovery window, one or more NAN terminals may transmit synchronizationbeacon frames to help all NAN terminals in the NAN cluster tosynchronize the clock.

The NAN sync beacon frame is transmitted in a dispersive manner. The NANsync beacon frame may be transmitted in a discovery window durationwhich exists every 512 TUs. All NAN terminals may participate in thecreation and transmission of the NAN sync beacon frame according to therole and state of the device. Each NAN terminal shall maintain its ownTSF timer used for NAN beacon cycle timing.

The transmission duration of the NAN sync beacon frame may be set by theNAN terminal which creates the NAN cluster. A series of target beacontransmission times (TBTTs) is defined such that the discovery windowduration capable of transmitting the NAN sync beacon frame is separatedexactly by 512 TUs. A time 0 is defined as a first TBTT, and a discoverywindow starts at each TBTT.

Each NAN terminal playing a role of the NAN master may transmit the NANdiscovery beacon frame in a duration other than the NAN discoverywindow. On average, the NAN master may transmit the NAN discovery beaconframe every 100 TUs. A time between successive NAN discovery beaconstransmitted by one NAN master is less than or equal to 200 TUs.

If a scheduled transmission time of the NAN discovery beacon frameoverlaps with the NAN discovery window duration of the NAN cluster, theNAN master may skip transmission of the NAN discovery beacon frame. Tominimize power for transmission of the NAN discovery beacon frame, theNAN master may transmit the NAN discovery beacon frame in acontention-based manner on the basis of a channel access parametercorresponding to AC (access category)_VO (voice).

In addition, the NAN terminal may transmit the NAN service discoveryframe within the discovery window duration. The NAN service discoveryframe may be transmitted by all NAN terminals. That is, the NAN terminaltransmits a NAN service discovery frame and/or a synchronous beaconframe in a contention-based manner between a start (TStartDW) point ofthe discovery window and an end point (TEndDW) of the discovery window.If the NAN terminal is in a master or non-master sync state, the NANservice discovery frame and the NAN sync beacon frame may all betransmitted in the same discovery window.

Hereinafter, in an embodiment of the present invention, it is discloseda case where a NAN device in AP capability temporarily defers (orinterrupts) a service of a Wi-Fi mode in the same channel whileoperating in the Wi-Fi mode based on IEEE 802.11, and operates byswitching to the aforementioned NAN-based NAN mode. The NAN terminal inAP capability may operate in the WiFi mode to provide an IEEE802.11-based WiFi service on a basic service set (BSS) basis. The NANterminal in AP capability may also operate in the NAN mode to providethe NAN-based NAN service on the basis of a NAN cluster. In other words,it can be said that the WiFi mode supports BSS-based communication, andthe NAN mode supports communication based on the NAN cluster.

When the NAN terminal in AP capability operates in the NAN mode, a Wi-Fimode based service for a Wi-Fi mode STA associated with the NAN terminalin AP capability is interrupted, and a scanning operation of the Wi-Fimode STA for scanning the NAN terminal in AP capability may not benormally performed.

In the embodiment of the present invention, a method is disclosed inwhich, when the NAN terminal in AP capability is switched from the WiFimode to the NAN mode, the NAN terminal in AP capability transmitsinformation regarding an operation related to the NAN mode to an STAwhich intends to perform communication based on the WiFi mode.

Hereinafter, the STA operating in the WiFi mode is an STA operatingbased on IEEE 802.11, and may be expressed by the term “WiFi mode STA”.In addition, hereinafter, the STA operating in the NAN mode may beexpressed by the term “NAN terminal (or NAN mode STA)”.

FIG. 9 is a conceptual view illustrating a NAN mode operation of a NANterminal in AP capability.

In FIG. 9, it is disclosed a basic operation of the NAN terminal in APcapability when the NAN terminal in AP capability operates as a NANmaster.

Referring to FIG. 9, as described above, NAN terminals may periodicallytransmit a NAN sync beacon frame to synchronize with each other. Inaddition, the NAN terminals may periodically transmit a NAN servicediscovery frame for mutual discovery for a service to be provided. TheNAN terminal in AP capability, which operates as the NAN master, mayperiodically transmit a NAN discovery frame. The NAN terminal in APcapability, which operates as the NAN master, may also transmit the NANsync beacon frame and the NAN service discovery frame.

More specifically, the NAN terminal in AP capability, which is operatingin a Wi-Fi mode in a channel 6, may be switched to the NAN mode fortransmission of the NAN sync beacon frame, the NAN discovery beaconframe, and the NAN service discovery frame. In this case, a WiFi modeSTA associated with the existing NAN terminal in AP capability, whichoperates in the channel 6, and a WiFi mode STA which intends to beassociated with the NAN terminal in AP capability by scanning thechannel 6 may perform an abnormal operation due to switching to the NANmode of the AP. That is, when the NAN terminal in AP capability isswitched to the NAN mode, the WiFi mode STA cannot perform a normaloperation based on the WiFi mode, and cannot receive the WiFi-basedservice from the NAN terminal in AP capability. Therefore, it isnecessary to inform the WiFi mode STA of the switching to the NAN modeof the NAN terminal in AP capability.

Hereinafter, in an embodiment of the present invention, it is discloseda method in which a NAN terminal in AP capability informs a WiFi modeSTA of information regarding a NAN mode operation of the NAN terminal inAP capability when the NAN terminal in AP capability is switched from aWi-Fi mode to a NAN mode to transmit a NAN sync beacon frame, a NANservice discovery frame, and a NAN discovery beacon frame.

FIG. 10 is a conceptual view illustrating an operation of a NAN terminalin AP capability in a NAN mode according to an embodiment of the presentinvention.

In FIG. 10, it is disclosed a method in which a NAN terminal in APcapability informs a WiFi mode STA of information regarding a NAN modeoperation of the NAN terminal in AP capability.

Referring to FIG. 10, the NAN terminal in AP capability may transmit aCTS-to-self frame 1000 before transmitting a NAN frame 1020 (e.g., a NANsync beacon frame, a NAN service discovery frame, or a NAN discoveryframe). Hereinafter, for convenience, it is assumed in the embodiment ofthe present invention that the NAN terminal in AP capability uses theCTS-to-self frame 1000 to deliver information regarding the NAN modeoperation of the NAN terminal in AP capability to the WiFi mode STA.However, information regarding the NAN mode operation of the NANterminal in AP capability may be delivered to the WiFi mode STA througha frame other than the CTS-to-self frame 1000 (an existing frame or anewly defined frame (e.g., a network allocation vector (NAV) settingframe)), and such an embodiment may also be included in the scope of thepresent invention.

The CTS-to-self frame 1000 transmitted by the NAN terminal in APcapability may include duration information. The duration informationincluded in the CTS-to-self frame 1000 may be used for NAV setting ofthe WiFi mode STA. The duration information included in the CTS-to-selfframe 1000 may occasionally indicate different time durations. The NAVmay be an indicator indicating a time duration during which transmissionof a frame is impossible by the STA, irrespective of a result of sensingwhether a medium is busy or idle on the basis of a clear channelassessment (CCA) function of the STA. If the NAV is set, transmission ofthe frame of the STA is impossible during the indicated time duration.

For example, the NAN terminal in AP capability may be switched to theNAN mode to transmit the CTS-to-self frame 1000 before transmitting theNAN sync beacon frame. In this case, the CTS-to-self frame 1000 mayinclude duration information indicating a time duration in which the NANterminal in AP capability transitions back to the WiFi mode aftertransitioning to the NAN mode to transmit the NAN sync beacon frame.

The NAN terminal in AP capability may be switched to the NAN mode totransmit the CTS-to-self frame 1000 before transmitting the NAN servicediscovery frame. In this case, the CTS-to-self frame 1000 may includeduration information indicating a time duration in which the NANterminal in AP capability transitions back to the WiFi mode aftertransitioning to the NAN mode to transmit the NAN service discoveryframe.

The NAN terminal in AP capability may be switched to the NAN mode totransmit the CTS-to-self frame 1000 before transmitting the NANdiscovery beacon frame. In this case, the CTS-to-self frame 1000 mayinclude duration information indicating a time duration in which the NANterminal in AP capability transitions back to the WiFi mode aftertransmitting the NAN discovery beacon frame by transitioning to the NANmode.

The duration information may indicate a time duration from thetransmission of the CTS-to-self frame 1000 to the switching to the WiFimode.

Upon receiving the CTS-to-self frame 1000 transmitted by the NANterminal in AP capability, the NAN terminal sets the NAV for a durationwhich is set based on the duration information included in theCTS-to-self frame 1000, and may transition to a doze state.Alternatively, the WiFi mode STA may not perform transmission of a framewhile maintaining an awake state during the set duration, and thereaftermay transmit a frame after the set duration.

If the NAN terminal in AP capability is switched to the NAN mode, thetransmitted CTS-to-self frame 1000 may be received not only by the WiFimode STA but also by the NAN terminal. The CTS-to-self frame 1000 is fortemporary interruption of the WiFi mode of the NAN terminal in APcapability and for initiation of the NAN mode of the NAN terminal in APcapability based on the NAN mode. Therefore, when the NAN terminalreceives the CTS-to-self frame 1000, the NAN terminal should not set theNAV duration on the basis of the CTS-to-self frame 1000. This is becausethe NAN terminal needs to receive the NAN sync beacon frame, NANdiscovery beacon frame, and NAN service discovery frame transmitted bythe NAN terminal in AP capability, which operates in the NAN mode.Therefore, according to the embodiment of the present invention, theduration field included in the CTS-to-self frame 1000 transmitted by theNAN terminal in AP capability may separately indicate whether to set anNAV of each of the NAN terminal and the WiFi mode STA.

FIG. 11 is a conceptual view illustrating a CTS-to-self frame accordingto an embodiment of the present invention.

In FIG. 11, a duration field included in the CTS-to-self frame isdisclosed.

Referring to FIG. 11, a medium access control (MAC) header 1100 of theCTS-to-self frame may include a duration field 1120.

According to the embodiment of the present invention, the duration field1120 may indicate whether to set a NAV (or whether to set a NAVduration) of a NAN terminal and/or a WiFi mode STA.

For example, the duration field 1120 of the CTS-to self frame may havetwo octets. According to a value of a least significant bit (LSB) 1 bitor a most significant bit (MSB) 1 bit among a plurality of bitsconstituting the duration field 1120, both of the NAN terminal and theWiFi mode STA may set the NAV duration or only the WiFi mode STA may setthe NAV duration. A bit indicating whether to set the NAV (or whether toset the NAV duration) of the NAN terminal and/or the WiFi mode STA amongthe bits included in the duration field 1120 may be expressed by theterm “NAV setting target indication bit 1140”.

For example, if a value of the NAV setting target indication bit 1140 is0, both of the NAN terminal and the WiFi mode STA may decode theduration field to instruct to set the NAV (or the NAV duration) on thebasis of the duration field. On the contrary, if the value of the NAVsetting target indication bit 1140 is 1, the NAN terminal may ignore NAVsetting based on the duration field and only the WiFi mode STA mayinstruct to perform NAV setting based on the duration.

The remaining bits (e.g., 15 bits) of the bits (e.g., 16 bits)constituting the duration field 1120, except for the NAV setting targetindication bit (e.g., 1 bit) 1140, may be a duration information bit1160 for the NAV setting.

That is, the NAN terminal may receive the CTS-to-self frame from the NANterminal in AP capability, and may determine whether the NAV settingtarget indication bit 1140 included in the CTS-to-self frame is setto 1. If the NAV setting target indication bit 1140 is set to 1, the NANterminal may receive the NAN sync beacon frame, NAN discovery beaconframe, and NAN service discovery frame transmitted by the NAN terminalin AP capability by ignoring information included in the duration fieldof the CTS-to self frame and by maintaining an awake state.

FIG. 12 is a conceptual view illustrating a CTS-to-self frame accordingto an embodiment of the present invention.

In FIG. 12, a CTS-to-self frame which is valid only for a WiFi mode STAis disclosed.

Referring to FIG. 12, a part of a reserved bit of a subtype field 1200included in a frame control field included in a MAC header of aCTS-to-self frame may indicate whether the CTS-to-self frame is aCTS-to-self frame which is valid only for a WiFi mode STA.

Before switching to a NAN mode, a NAN terminal in AP capability maytransmit in a broadcast manner the CTS-to-frame including the subtypefield 1200 of the frame control field indicating that the CTS-to-selfframe is valid only for the WiFi mode STA. That is, the subtype field1200 of a specific value may indicate that the CTS-to-self frame is forthe WiFi mode STA, and an AP may transmit to an STA the subtype field1200 indicating that it is for the WiFi mode STA through the CTS-to-selfframe.

In this case, the WiFi-mode STA which has received the CTS-to-self framemay set a NAN duration. The NAN terminal which has received theCTS-to-self frame may maintain an active mode, and may monitor andreceive a NAN sync beacon frame, NAN discovery beacon frame, and NANservice discovery frame to be transmitted by the NAN terminal in APcapability.

Other MAC header structures are disclosed in 8.2 MAC frame formats ofIEEE Standard for Information technology Telecommunications andinformation exchange between systems Local and metropolitan areanetworks Specific requirements Part 11: Wireless LAN Medium AccessControl(MAC) and Physical Layer (PHY) Specifications disclosed inOctober 2013.

FIG. 13 is a block diagram illustrating a wireless device according toan embodiment of the present invention.

Referring to FIG. 13, an AP 1300 includes a processor 1310, a memory1320, and a radio frequency (RF) unit 1330.

The RF unit 1330 may be coupled to the processor 1310 totransmit/receive a radio signal.

The processor 1310 may implement the functions, procedures, and/ormethods proposed in the present invention. For example, the processor1310 may be implemented to perform an operation of an AP according tothe aforementioned embodiment of the present invention. The processormay perform an operation of a NAN terminal in AP capability disclosed inthe embodiments of FIG. 1 to FIG. 12.

For example, the processor 1310 may be implemented to determineswitching from a wireless fidelity (WiFi) mode to a NAN mode, and if theswitching to the NAN mode is determined, to transmit a CTS-to-self frameon the NAN mode, switch from the WiFi mode to the NAN mode, and transmita NAN beacon frame to a NAN terminal on the NAN mode. The WiFi mode maysupport communication based on a basic service set (BSS), and the NANmode may support communication based on a NAN cluster.

The CTS-to-self frame may include a duration field, and the durationfield may include information on a duration until the NAN terminal in APcapability transitions back to the switching mode. The CTS-to-self framemay be received by a WiFi mode STA operating in the WiFi mode, and theWiFi mode STA may set a network allocation vector (NAV) during theduration.

The duration field may further include a NAV setting target indicationbit. If the NAV setting target indication bit indicates a first value,the NAN terminal and the WiFi mode STA may set a NAV during theduration. If the NAV setting target indication bit indicates a secondvalue, only the WiFi STA may set the NAV during the duration.

An STA 1350 includes a processor 1360, a memory 1370, and an RF unit1380.

The RF unit 1380 may be coupled to the processor 1360 totransmit/receive a radio signal.

The processor 1360 may implement the functions, procedures, and/ormethods proposed in the present invention. For example, the processor1360 may be implemented to perform an operation of the STA according tothe aforementioned embodiment of the present invention. The processor1360 may perform an operation of a NAN terminal (or a NAN mode STA) inthe embodiments of FIG. 1 to FIG. 12.

For example, if the STA is the NAN mode STA, the processor 1360 mayreceive the NAN beacon frame from the NAN terminal in AP capability,which operates as a NAN master. Further, the processor 1360 maydetermine whether to set an NAV on the basis of the NAN setting targetindication bit and duration information included in the CTS-to-selfframe.

For example, if the STA is the WiFi mode STA, the processor 1360 maydetermine whether to set the NAV on the basis of the NAN setting targetindication bit and duration information included in the CTS-to-selfframe.

The processors 1310 and 1360 may include application-specific integratedcircuits (ASICs), other chipsets, logical circuits, data processingdevices, and/or converters for mutually converting a baseband signal anda radio signal. The memories 1320 and 1370 may include a read-onlymemory (ROM), a random access memory (RAM), a flash memory, a memorycard, a storage medium and/or other storage devices. The RF units 1330and 1380 may include at least one antenna to transmit and/or receive theradio signal.

When the above-described embodiment is implemented in software, theabove-described scheme may be implemented using a module (procedure,function, etc.) which performs the above function. The module may bestored in the memories 1320 and 1370 may be and executed by theprocessors 1310 and 1360. The memories 1320 and 1370 may be disposed tothe processors 1310 and 1360 internally or externally and connected tothe processors 1310 and 1360 using a variety of well-known means.

What is claimed is:
 1. A method of scheduling a radio resource forneighbor awareness networking (NAN), the method comprising: determiningswitching from a wireless fidelity (WiFi) mode to a NAN mode by a NANterminal in access point (AP) capability; if the NAN terminal in APcapability determines the switching to the NAN mode, transmitting, bythe NAN terminal in AP capability, a clear to send (CTS)-to-self frameon the WiFi mode; switching, by the NAN terminal in AP capability, fromthe WiFi mode to the NAN mode; and transmitting, by the NAN terminal inAP capability, a NAN frame to the NAN terminal on the NAN mode, whereinthe WiFi mode supports communication based on a basic service set (BSS),and wherein the NAN mode supports communication based on a NAN cluster.2. The method of claim 1, wherein the CTS-to-self frame comprises aduration field, and wherein the duration field comprises information ona duration until the NAN terminal in AP capability transitions back tothe switching mode.
 3. The method of claim 2, wherein the CTS-to-selfframe is received by a WiFi mode STA operating in the WiFi mode, andwherein the WiFi mode STA sets a network allocation vector (NAV) duringthe duration.
 4. The method of claim 2, wherein the duration fieldfurther comprises a NAV setting target indication bit, wherein if theNAV setting target indication bit indicates a first value, the NANterminal and the WiFi mode STA set a NAV during the duration, andwherein if the NAV setting target indication bit indicates a secondvalue, only the WiFi STA sets the NAV during the duration.
 5. The methodof claim 2, wherein the NAV frame comprises a NAN sync beacon frame, aNAN discovery beacon frame, and a NAN service discovery frame, whereinif the NAN frame is the NAN sync beacon frame, the duration is a timeduration until the NAN terminal in AP capability transitions back to theswitching mode after the NAN sync beacon frame is transmitted, whereinif the NAN frame is the NAN discovery beacon frame, the duration is atime duration until the NAN terminal in AP capability transitions backto the switching mode after the NAN discovery beacon frame istransmitted, and wherein if the NAN frame is the NAN service discoveryframe, the duration is a time duration until the NAN terminal in APcapability transitions back to the switching mode after the NAN servicediscovery frame is transmitted.
 6. A neighbor awareness networking (NAN)terminal in access point (AP) capability for performing radio resourcescheduling for NAN, the NAN terminal in AP capability comprising: aradio frequency (RF) unit configured for transmitting or receiving aradio signal; and a processor operatively coupled to the RF unit,wherein the processor is configured for: determining switching from awireless fidelity (WiFi) mode to a NAN mode; if the switching to the NANmode is determined, transmitting a clear to send (CTS)-to-self frame onthe WiFi mode; switching from the WiFi mode to the NAN mode; andtransmitting a NAN frame to the NAN terminal on the NAN mode, whereinthe WiFi mode supports communication based on a basic service set (BSS),and wherein the NAN mode supports communication based on a NAN cluster.7. The NAN terminal in AP capability of claim 6, wherein the CTS-to-selfframe comprises a duration field, and wherein the duration fieldcomprises information on a duration until the NAN terminal in APcapability transitions back to the switching mode.
 8. The NAN terminalin AP capability of claim 7, wherein the CTS-to-self frame is receivedby a WiFi mode STA operating in the WiFi mode, and wherein the WiFi modeSTA sets a network allocation vector (NAV) during the duration.
 9. TheNAN terminal in AP capability of claim 7, wherein the duration fieldfurther comprises a NAV setting target indication bit, wherein if theNAV setting target indication bit indicates a first value, the NANterminal and the WiFi mode STA set a NAV during the duration, andwherein if the NAV setting target indication bit indicates a secondvalue, only the WiFi STA sets the NAV during the duration.
 10. The NANterminal in AP capability of claim 7, wherein the NAV frame comprises aNAN sync beacon frame, a NAN discovery beacon frame, and a NAN servicediscovery frame, wherein if the NAN frame is the NAN sync beacon frame,the duration is a time duration until the NAN terminal in AP capabilitytransitions back to the switching mode after the NAN sync beacon frameis transmitted, wherein if the NAN frame is the NAN discovery beaconframe, the duration is a time duration until the NAN terminal in APcapability transitions back to the switching mode after the NANdiscovery beacon frame is transmitted, and wherein if the NAN frame isthe NAN service discovery frame, the duration is a time duration untilthe NAN terminal in AP capability transitions back to the switching modeafter the NAN service discovery frame is transmitted.